The invention is based on a fuel injection valve for internal combustion engines.
One such fuel injection valve is known from German Patent Disclosure DE 198 13 983 A1. This fuel injection valve is a component of a storage-type fuel injection system and has an injection valve member by which at least one injection opening is controlled and which has a pressure shoulder defining a pressure chamber. Fuel under pressure can be delivered to the pressure chamber from a high-pressure fuel source via a pressure line, by means of which fuel the injection valve member can be lifted from a valve seat, counter to a closing force, to open the at least one injection opening. The motion of the injection valve member is influenced by a control valve, which has a control valve member that is movable by an adjusting force generated by a piezoelectric actuator and that controls the pressure, prevailing in a control pressure chamber communicating with a pressure source, which pressure urges the injection valve member in its closing direction. By means of the control valve member, the control pressure chamber can be made to communicate with a relief chamber, and as a result the pressure in the control pressure chamber drops, and the injection valve member can be moved in the opening direction. With a sealing face disposed on the control valve member, the control valve member cooperates with a valve seat. For rapid opening and closing of the fuel injection valve, as is necessary to achieve a preinjection, for instance, high adjusting forces for the control valve member are necessary and have to be generated by the piezoelectric actuator, in order to lift the control valve member from the valve seat and after its reversal of its direction of motion to return it to the valve seat again. The movement of the control valve member by the adjusting force generated by the piezoelectric actuator must furthermore be effected counter to the pressure prevailing in the control pressure chamber, so that a major force must be expended to move it. For these reasons, a piezoelectric actuator of large dimensions is required.
The fuel injection valve of the invention has the advantage over the prior art that by means of the control valve member, with a motion from one valve seat to the other, without a reversal of the direction of motion, a very rapid opening and closure of the fuel injection valve can be achieved, to which end furthermore only a slight adjusting force to be generated by the piezoelectric actuator is required, so that the piezoelectric actuator can be embodied with small dimensions.
By another embodiment it is attained that no force on the control valve member from the pressure in the control pressure chamber results, and as a result only a slight adjusting force to be generated by the piezoelectric actuator is needed to move the control valve member, and the piezoelectric actuator can be made with small dimensions. The further embodiment makes a compact structure of the control valve possible.